Self-cleaning aperture tube for coulter study apparatus

ABSTRACT

A two chamber aperture tube for obtaining signals from particles suspended in a fluid which passes through a scanning aperture. The suspension enters the primary bore provided in one chamber and passes immediately to an inlet port or orifice in an elongate nozzle provided in the second chamber. The chambers are interconnected by conduits including a pump and filter such that flow of the suspension is continuous about a closed path to ensure that proper signals from all particles in the suspension are obtained.

[111 E Re. 28,558

[ Reissued Sept. 23, 1975 0 United States Patent [191 Hogg [ SELF-CLEANING APERTURE TUBE FOR COULTER STUDY APPARATUS [75] Inventor: Walter R. Hogg, Miami Lakes, Fla.

[73] Assignee: Coulter Electronics, Inc., Hialeah,

Fla.

[22] Filed: June 10, 1974 [21] Appl. No.: 477,760

Related U.S. Patent Documents Reissue of:

[64] Patent No.: 3,746,976

Issued: July 17, 1973 Appl. No.: 131,923

Filed: Apr. 7, 1971 [52] U.S. C1. 324/71 CP [51] Int. Cl. G01N 27/00 [58] Field of Search .1 324/71 CP [56] References Cited UNITED STATES PATENTS 3,299,354 l/1967 Hogg 324/71 CP 3,583,209 6/1971 Banks 73/432 PS Primary ExaminerRobert J. Corcoran Assistant Examiner Rolf Hille Attorney, Agent, or Firm-Silverman & Cass, Ltd.

[57] ABSTRACT A two chamber aperture tube for obtaining signals from particles suspended in a fluid which passes through a scanning aperture. The suspension enters the primary bore provided in one chamber and passes immediately to an inlet port or orifice in an elongate nozzle provided in the second chamber. The chambers are interconnected by conduits including a pump and filter such that flow of the suspension is continuous about a closed path to ensure that proper signals from all particles in the suspension are obtained.

14 Claims, 3 Drawing Figures Z l r I, I i 1 I i l 5 I 7 i i I f Reissued Sept. 23,1975 Re. 28,558

EESEKVOIE //VV/VT(-)R: WALTER R. H066 specific reference.

SELF-CLEANING APERTURE-TUBE FOR COULTER STUDY APPARATUS Matter enclosed heavy brackets; I: the original patentbut forms no part this reissue specification; matter printed in italics indicates theadditions niade by reissue. I

CROSS-REFERENCE TO RELATED PATENT The structure to which this invention applies is of the typedescribed and'discl osed i n US. Pat. No. 3,299,354 (herein called the Related Patent lis'sued' lanj 17, 1967 for Aperture Tube Structure for ParticleStudy Apparatus" to the same inventor, and owned by the same assignee, as the invention herein. The said Related Patent is incorporated herein as part hereof by BACKGROUND OF THE INVENTION s 1. Field of the Invention g This invention relates generally to the art of studying the physical properties'of particles carried "in suspension and more particularly is concerned with'improved apparatus for obtaining signals from particles passing through a scanning aperture without extraneous interfere'nce from other particles.

2. Description of the Prior Art The structure disclosed-in theRelated'Patent substantially decreases the possibility of undesirable-spurious particle reading and count-signals whichoc'curred in prior art devices. This is accomplished by replacing the so 'called aperture tube of prior artstructures with a pair ofchambers having'an interconnection for sepa rating the electrical and mechanical effects of the particles passing through the aperture. Particles passing through the aperture of the apparatus immediately are transported away from the proximity of the aperture so that there is little or no change of spurious signals re sulting from said particles.

One of the objects-of the invention disclosed in the Related Patent was to provide an aperture tube which is self-cleaning in that the suspension in the immediate vicinity of the aperture is kept free ofex-traneous particles. As acknowledged-in thepatent; however, eddy cles, hence not-introducing appreciable extraneous signals, but while this was largely true, the. action was not.

sufficiently perfect to satisfy the morecritical demands of .today-fs technology. A smallv percentage of particles were not caught by theprifice inthe elongate neck the second chamber and these sometimes produced ex trancous signals by; v-irtue zofthe eddy currents at the ottom of the central .c harrrber of. the apert pretube SUMMARY OF'THE "IINVENTIQN h To resolve aforesaid problems with regard to exfl q n th wsmtinwnfien. P Q i a e s tifi a e t reb as d 1$ -.in str a d la -.1 tent, with the addition of a purnp device, interposed be tween the first and second chambers 1o produce ;a closed system in which gtherc .ar e no inletsor outlets.

associated elements designated generally by the referother=than the primary bore inzthe first chamber; :The pump operates to draw the particle suspension up through the. second chamber' and force the same'back intothe first chamber, completinga circuit around this .path .and creating a sheath flow at the orifice. The flow created by the pumpis such as to ensure that all particlesintroduced into the aperture tube-are caught by the .orificeof the. second chamber so as to prevent the occurrence of extraneous signalsa I v- -Accordingly, the primary object of the inventionis to provide an improved structure; which ensures that all particles passing through the primary. bore are; caught by the .orifice. provided in the second chamber of the .apermretube. i

--Other objects and advantages of, theinvention will occurito thoseskilledin this ant as a description of the inven-tionz-proceeds in connectionwith which a pre-. ferred embodiment is illustrated in*the accompanying drawings and set forth in the accompanying specification. I

' LBRIEFDESC RTPTION oFfrueoaAwm' j The drawing isv identical to that of the Related Patent, except for those elements. added thereto in accordance with the invention herein, r 1 i FIG. .1 .se ctional view through the apparatus of the RelatedPatenLqwith the pump deviceand related elements of the invention illustrated in.- diagrammatic form. :w'. -,FIG. 2 is a fragmentary enlarged sectional view through the apparatus in the-vicinity (lithe-aperture.-

FIG. 3 is a diagrammatic ,vie. w of a device operating. in connection with the manometer-Syphon having the improved invention associated therewith, n

DESCRIPTION or Tria PR'Efi RREo "EMB DI EN ln thehfollowing description, elements which a identicalto those disclosed ingthe related patent are re;

ferred-to herein by the" same names and-are indicated by the sameareference,numerals. Since the'related pa. tent. is incorporated herein as a part hereof byspecific; reference the;diselosure thereof will not be-repeated except in instances where understanding of the invert-1:

tionhereinwilhbe. enhanced. I A

;.,As illustratedvi-n'FlG, .1, a multiple chamber. aperture. tube or vessel 14, comprising a first or central chamber 321ancl secondchamber 34 is suspended within a vessel 10,-ln operation, the suspension loin vessel l0 will would then continue to discharge conduit 58 by way of passage 54. of stop-cock 56.

In order to .ensure that all particles in suspension 1.6 are-caughtflby orifice 40 {as they flow through aperture 12 5? .5, pparatus of the invention includes a pump and illustrated, a pair'of Tjunctions 7, 8 have been spliced into branch 52 and conduit 62, respectively, so as to .in-

troduce the elements 6 into the flow system represented by the solid line arrows throughout the aperture tube .14. A conduit 2 leads through a filter.4 into pump.

1 from junction 7, and conduit 3 leads out of pump 1 into junction 8.

It is to be understood that the points of entry 7, 8 into the two chambers 32, 34 could be made at any point along the lengths thereof. The particular location shown is for illustrative purposes only.

The addition of the elements 6 to the system of the related patent produces a closed system within the aperture tube 14 whereby, upon operation of pump 1, suspension 16 is sucked through neck 36, up chamber 34, and through conduits 46, 50 and 2. The suspension then passes through filter 4, where the particles suspended therein are removed, and into pump 1. The particle free suspending liquid 16 is then forced back into chamber 32 by way of conduits 3 and 62, completing a circuit around this path and creating a sheath flow at orifice 40. The sample flow as described in the related patent will be unaffected since this closed system has no other inlets or outlets.

Operation of pump 1 ensures that all particles in suspension 16 are caught by the orifice 40 as they pass through aperture 12. The added flow of clean suspension fluid, indicated by arrows 5 in FIG. 2, serves further to sweep the region of secondary bore 22 free of all particles which are extraneous to those on which the sensing operation is performed. By adjustment of the pump pressure, the sheath flow 5 will be of proper strength to ensure that all particles pass directly into orifice 40.

The operation and functions of all remaining elements illustrated in the drawing are the same as described in the related patent.

I claim:

1. In a particle measuring apparatus including a container of particulate liquid suspension to be tested, an aperture tube extending into said container, a vacuum source for moving the liquid from the container into and through the aperture tube, a first electrode in the container and a second electrode in the aperture tube to establish an electrical field between said container and the aperture tube, and a detector, the aperture tube having a first and a second chamber, the first chamber having an aperture in communication with the liquid suspension in the container. said second chamber having an orifice provided therein at a point closely spaced from and directly opposite the interior of said aperture, means connecting said second chamber to said vacuum source and means to initially fill the first chamber with particle free liquid and the second chamber with the liquid suspension, the improvement comprising, a conduit extending between said chambers to provide a closed path for liquid flow thcrebetwecn, a pump interposed in said conduit to create liquid flow about said path, and a filter member in said conduit, whereby the suspension will flow from the container through the aperture and the orifice into said second chamber to mix with the liquid already therein and circulate about said path, said filter member removing the particles from the liquid before the same'is returned to the first chamber.

2. The structure as claimed in claim 1 in which an elongate neck extends from the second chamber into the first chamber and said orifice is provided in said neck.

3. An aperture tube for use in particle measuringapparatus including a container of particulate liquid suspension into which the aperture tube extends, said tube including a firstandasecond chamber, the first chamber having'an aperture in communication with the liquid suspension, said second chamber having an orifice provided therein at a location directly opposite the interior of said aperture, means for connecting said second chamber to an external source of vacuum, conduit means extending between said chambers to provide a closed path for liquid flow therebetween, a pump interposed in said conduit means to create liquid flow about said path, and a filter member in said conduit means, whereby the suspension will flow through said aperture in the first chamber and through said orifice in the second chamber and then through said conduit and said pump and said filter member where the particles from the suspension are removed before the same is forced into the first chamber and returned through said orifice.

4. An aperture tube as claimed in claim 3 in which an elongate neck extends from said second chamber into said first chamber and said orifice is provided in said neck.

5. In a particle measuring apparatus which responds to the changes of electrical impedance due to the displacement of electrolyte by particles suspended therein in an aperture which constricts an electric field, including a container of liquid suspension to be tested, a dualchamber aperture tube having a first and a second chamber extending into said container, a vacuum source for moving the liquid from the container into and through the aperture tube, a first electrode in the container and a second electrode in the aperture tube to establish the electric field, and a detector, the first chamber having an aperture forming a communication between said container and said first chamber, the second chamber having an orifice forming a communica tion between said first and said second chambers, said orifice being positioned close to and directly opposite said aperture, the improvement comprising, means for preventing particles from the contents of the container from being transferred to suspension in the contents of the first chamberv 6. The structure as claimed in claim 5 in which said means comprises a conduit extending between said chambers to provide a closed path for liquid flow therebetween, a pump interposed in said conduit to create liquid circulation about said path, and a filter for removing particles from the circulating liquid, such that the volume of liquid which flows into said orifice is the sum of the circulation about said closed path plus the flow from said container into said first chamber.

7. The structure as claimed in claim 6 in which said vacuum source is adapted to withdraw liquid from the low pressure side of said pump.

8. The structure as claimed in claim 7 in which an elongate neck extends from the second chamber into the first chamber and said orifice is provided in said neck.

9. The structureas claimed in claim 7 in which filling means are provided to fill the aperture tube, said conduit and said pump with liquid prior to performing the first test of particle suspension contained in said container.

10. The structure as claimed in claim 9 in which said filling means comprise a two-way stopcock and an open-close stopcock, said two-way stopcock being adapted to apply vacuum either to said first or said second chamber or to neither; said open-close stopcock being adapted to connect one chamber to a reservoir of suspension liquid.

11. The structure as claimed in claim in which an elongate neck extends from the second chamber into the first chamber and said orifice is provided in said neck.

12. In a particle measuring apparatus including a vessel for containing a body of particulate liquid suspension to be tested, an aperture tube extending into said vessel and including an aperture,fluid moving meansfor establishing pressure differentials and adapted for moving the suspension from the vessel through the aperture into and through the aperture tube to a waste collection container, a first electrode in the vessel and a second electrode in the aperture tube to establish an electrical field in the aperture between said vessel and the aperture tube, means in cluding electrical leads connected to the electrodes and adapted to extend connections to a detector to respond to electrical measuring signals produced across said electrodes with passage of particles through said aperture, the aperture tube having an inlet chamber adapted for fluid connection with a source of particle free liquid, said inlet chamber having said aperture in fluid communication on one side thereof with the suspension in the vessel to permit passage of the suspension through the aperture into the inlet chamber, there being a zone in the aperture tube proximate to and downstream of the aperture in which spurious signals may normally be produced, an outlet chamber in fluid connection with said inlet chamber, means for connecting said outlet chamber to said fluid moving means and said waste collection container, means for initially filling the inlet and outlet chambers with particle free liquid; the improvement comprising, said aperture tube having a restriction in the path of flow of said particle free liquid to cause the flow velocity thereof to increase in the spurious signal producing zone and continuously to wash the zone simultaneously wit/1 passage of the suspension through the aperture such that particles which have been measured within the aperture while the apparatus is in use for measuring particles and the means for initially filling the inlet and outlet chambers are rendered inoperative and thereafter passing out of the same immediately are swept out of the spurious signal producing zone by the particle free liquid and moved into the outlet chamber.

13. The invention as claimed in claim 12 in which said fluid moving means comprise a source of vacuum.

14. An aperture tube for use in particle measuring apparatus including a container of particulate liquid suspension into which the aperture tube extends, said tube comprising, an inlet chamber, an outlet chamber in fluid connection with the inlet chamber, the inlet chamber having an aperture adapted to be in communication on one side thereof with the liquid suspension, there being a zone in the aperture tube proximate to and downstream of the aperture in which spurious signals may normally be produced, means for connecting the inlet chamber to a source of particle free liquid, means for directing flow of said particle free liquid from said source into and through said inlet chamber and thereafter into and through said outlet chamber, means for connecting the outlet chamber to fluid moving means to more the suspension from the container through the aperture into the spurious signal producing zone while said particle free fluid is so flowing, the tube having a restriction in the path offlow of the particle free liquid to cause the flow velocity thereof to increase in the spurious signal producing zone and continuously wash the zone simultaneously wit/1 passage oft/1e suspension through the aperture such that particles which have passed through the aperture immediately are swept out of the spurious signal producing zone by the particle free liquid and moved into the outlet chamber. 

1. In a particle measuring apparatus including a container of particulate liquid suspension to be tested, an aperture tube extending into said container, a vacuum source for moving the liquid from the container into and through the aperture tube, a first electrode in the container and a second electrode in the aperture tube to establish an electrical field between said container and the aperture tube, and a detector, the aperture tube having a first and a second chamber, the first chamber having an aperture in communication with the liquid suspension in the container, said second chamber having an orifice provided therein at a point closely spaced from and directly opposite the interior of said aperture, means connecting said second chamber to said vacuum source and means to initially fill the first chamber with particle free liquid and the second chamber with the liquid suspension, the improvement comprising, a conduit extending between said chambers to provide a closed path for liquid flow therebetween, a pump interposed in said conduit to create liquid flow about said path, and a filter member in said conduit, whereby the suspension will flow from the container through the aperture and the orifice into said second chamber to mix with the liquid already therein and circulate about said path, said filter member removing the particles from the liquid before the same is returned to the first chamber.
 2. The structure as claimed in claim 1 in which an elongate neck extends from the second chamber into the first chamber and said orifice is provided in said neck.
 3. An aperture tube for use in particle measuring apparatus including a container of particulate liquid suspension into which the aperture tube extends, said tube including a first and a second chamber, the first chamber having an aperture in communication with the liquid suspension, said second chamber having an orifice provided therein at a location directly opposite the interior of said aperture, means for connecting said second chamber to an external source of vacuum, conduit means extending between said chambers to provide a closed path for liquid flow therebetween, a pump interposed in said conduit means to create liquid flow about said path, and a filter member in said conduit means, whereby the suspension will flow through said aperture in the first chamber and through said orifice in the second chamber and then through said conduit and said pump and said filter member where the particles from the suspension are removed before the same is forced into the first chamber and returned through said orifice.
 4. An aperture tube as claimed in claim 3 in which an elongate neck extends from said second chamber into said first chamber and said orifice is provided in said neck.
 5. In a particle measuring apparatus which responds to the changes of electrical impedance due to the displacement of electrolyte by particles suspended therein in an aperture which constricts an electric field, including a container of liquid suspension to be tested, a dual-chamber aperture tube having a first and a second chamber extending into said container, a vacuum source for moving the liquid from the container into and through the aperture tube, a first electrode in the container and a second electrode in the aperture tube to establish the electric field, and a deTector, the first chamber having an aperture forming a communication between said container and said first chamber, the second chamber having an orifice forming a communication between said first and said second chambers, said orifice being positioned close to and directly opposite said aperture, the improvement comprising, means for preventing particles from the contents of the container from being transferred to suspension in the contents of the first chamber.
 6. The structure as claimed in claim 5 in which said means comprises a conduit extending between said chambers to provide a closed path for liquid flow therebetween, a pump interposed in said conduit to create liquid circulation about said path, and a filter for removing particles from the circulating liquid, such that the volume of liquid which flows into said orifice is the sum of the circulation about said closed path plus the flow from said container into said first chamber.
 7. The structure as claimed in claim 6 in which said vacuum source is adapted to withdraw liquid from the low pressure side of said pump.
 8. The structure as claimed in claim 7 in which an elongate neck extends from the second chamber into the first chamber and said orifice is provided in said neck.
 9. The structure as claimed in claim 7 in which filling means are provided to fill the aperture tube, said conduit and said pump with liquid prior to performing the first test of particle suspension contained in said container.
 10. The structure as claimed in claim 9 in which said filling means comprise a two-way stopcock and an open-close stopcock, said two-way stopcock being adapted to apply vacuum either to said first or said second chamber or to neither, said open-close stopcock being adapted to connect one chamber to a reservoir of suspension liquid.
 11. The structure as claimed in claim 10 in which an elongate neck extends from the second chamber into the first chamber and said orifice is provided in said neck.
 12. In a particle measuring apparatus including a vessel for containing a body of particulate liquid suspension to be tested, an aperture tube extending into said vessel and including an aperture, fluid moving means for establishing pressure differentials and adapted for moving the suspension from the vessel through the aperture into and through the aperture tube to a waste collection container, a first electrode in the vessel and a second electrode in the aperture tube to establish an electrical field in the aperture between said vessel and the aperture tube, means including electrical leads connected to the electrodes and adapted to extend connections to a detector to respond to electrical measuring signals produced across said electrodes with passage of particles through said aperture, the aperture tube having an inlet chamber adapted for fluid connection with a source of particle free liquid, said inlet chamber having said aperture in fluid communication on one side thereof with the suspension in the vessel to permit passage of the suspension through the aperture into the inlet chamber, there being a zone in the aperture tube proximate to and downstream of the aperture in which spurious signals may normally be produced, an outlet chamber in fluid connection with said inlet chamber, means for connecting said outlet chamber to said fluid moving means and said waste collection container, means for initially filling the inlet and outlet chambers with particle free liquid; the improvement comprising, said aperture tube having a restriction in the path of flow of said particle free liquid to cause the flow velocity thereof to increase in the spurious signal producing zone and continuously to wash the zone simultaneously with passage of the suspension through the aperture such that particles which have been measured within the aperture while the apparatus is in use for measuring particles and the means for initially filling the inlet and outlet chambers are rendered inoperative and thereafter passing out of the same immediately are swept out of the spurious signal producing zone by the particle free liquid and moved into the outlet chamber.
 13. The invention as claimed in claim 12 in which said fluid moving means comprise a source of vacuum.
 14. An aperture tube for use in particle measuring apparatus including a container of particulate liquid suspension into which the aperture tube extends, said tube comprising, an inlet chamber, an outlet chamber in fluid connection with the inlet chamber, the inlet chamber having an aperture adapted to be in communication on one side thereof with the liquid suspension, there being a zone in the aperture tube proximate to and downstream of the aperture in which spurious signals may normally be produced, means for connecting the inlet chamber to a source of particle free liquid, means for directing flow of said particle free liquid from said source into and through said inlet chamber and thereafter into and through said outlet chamber, means for connecting the outlet chamber to fluid moving means to move the suspension from the container through the aperture into the spurious signal producing zone while said particle free fluid is so flowing, the tube having a restriction in the path of flow of the particle free liquid to cause the flow velocity thereof to increase in the spurious signal producing zone and continuously wash the zone simultaneously with passage of the suspension through the aperture such that particles which have passed through the aperture immediately are swept out of the spurious signal producing zone by the particle free liquid and moved into the outlet chamber. 